Methods and systems for manufacturing yarns for synthetic turf

ABSTRACT

Systems and methods for manufacturing synthetic yarns for synthetic turf. The systems and methods include rollers for advancing a plastic sheet forward through a manufacturing process. The plastic sheet is cooled and heated on opposing sides by alternating temperature rollers to pre-form the plastic sheet such that subsequent synthetic yarns made from the sheet will have a curled shape. The plastic sheet is then cut longitudinally by a plurality of slitting blades along the length of the sheet to form a plurality of single strand synthetic yarns. A drawing device then draws and stretches the single strand synthetic yarns to a desired width and thickness, wherein the drawing device includes a drawing oven for heating the yarns, and a plurality of drawing rollers for pulling and stretching the heated yarns. The final product drawn yarns comprise sealed, smooth yarns with desirable rounded edges and a curled tip.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent No. 60/891,387, filed Feb. 23, 2007, and entitled“Method and Apparatus for Manufacturing Yarns for Synthetic Turf,” whichis incorporated herein by reference in its entirety.

FIELD OF THE PRESENT INVENTION

The present invention relates generally to manufacturing yarns forsynthetic turf. More particularly, the present invention relates tomethods, devices, and systems for manufacturing yarns for synthetic turfthat are resilient, retain infill, and have improved appearance andtexture.

BACKGROUND OF THE PRESENT INVENTION

Synthetic turf is a surfacing material used to imitate grass. It isgenerally used in areas where grass cannot grow, or in areas where grassmaintenance is impossible or undesired. Synthetic turf may be used inseveral applications, including indoor and outdoor synthetic puttinggreens, golf short game facilities, indoor practice facilities, golfdriving range tee mats and target greens, sports fields (such asfootball, soccer, rugby, bocce, tennis, baseball, lacrosse, etc.),lawns, parks, playgrounds, athletic fields, school play yards, cruiseships, hotels, other hospitality settings, and many other applications.

Synthetic turf is produced with a tufting process. A large number ofneedles insert synthetic yarn into a fabric or rubber backing structure.Then, a flexible adhesive such as polyurethane is used to bind thefibers to the backing structure. This process is similar to theprocedure used to create the majority of residential and commercialcarpets.

The fibers or yarns that make up the blades of “grass” for syntheticturf are typically made of a plastic material, such as nylon,polypropylene, linear low density polyethylene (hereinafter “LLDPE”), orany combination of these materials. Generally, these plastic materialsare extruded into either thin sheets or individual strands, and are thendrawn via a conventional drawing process to stretch and thin the sheetsor strands.

One conventional method of manufacturing the fibers that make up the“grass” blades from an extruded sheet is called “fibrillation,” whichessentially involves punching holes or slits in the plastic sheet afterit has been drawn. Even though the plastic sheet is being cut and slit,however, the plastic sheet remains in one piece. Usually, the plasticsheet is then further cut into sections having a width of approximately1 inch, and these sections (each of which still contains multiple“grass” strands connected together) are used in the tufting process tomake the synthetic turf.

The cutting in the fibrillation process is accomplished by hammering theplastic sheet with a roller that includes a large number of pins on itsouter surface, and the roller tears and cuts the sheet as the sheetmoves forward along the processing line. Often, the cuts in the sheetcreate a honeycomb-like pattern, such that the end result is an intactsheet with multiple strands connected together that resemble theappearance of grass.

While the fibrillating process may be cheap and easy, there are severaldisadvantages associated with synthetic turf made from fibrillated“grass” blades. Because of the violent method in which the plasticsheets are cut, the resulting blades of “grass” have sharp or roughedges, which are undesirable because they present a more abrasivesurface that can cause injury or irritation if someone slides or fallson the turf. Also, because of the forceful manner in which these plasticsheets are punctured and slit, the deterioration of the fibers begins assoon as the fibers are put into use. This deterioration is enhanced bybrushing machines containing rigid bristles that are often used to sweepaway fibers that have been torn from the turf. These brushing machinesfurther break apart and tear the fibers, and typically accelerate theoverall weakening of the turf. Additionally, because the strands of“grass” are lumped together into sections, and are not individual anddiscrete, the fibrillated synthetic turf lacks the look and feel of realgrass.

To combat the abrasive, non-resilient nature of the fibrillated fibers,another type of fiber, typically called “monofilament” fiber, is createdby extruding the plastic material through a die or spinneret to createseveral discrete strands of fiber. These monofilament fibers areadvantageous over the fibrillated fibers because they are individual anddiscrete, so they more closely resemble real grass. Also, they have asmoother finish and feel as compared to fibrillated fibers.

However, because the monofilament fibers are straight and upright wheninstalled as synthetic turf, the rubber and sand used as infill aroundthe base of the fibers can blow away or be kicked around by players onthe turf because there is nothing keeping the infill in place. This lossor displacement of infill is commonly referred to as “flyout.” Overtime, flyout of infill results in a non-uniform, abrasive playingsurface, which is highly undesirable. Additionally, because each strandof monofilament fiber must be individually extruded, it can be difficultto easily and efficiently manufacture large quantities of the fibers.

Therefore, there exists a long-felt but unresolved need for syntheticyarns, or “grass” blades, for synthetic turf that are resilient toabuse, have smooth or rounded edges, retain infill and prevent flyout,are easy to efficiently mass produce, and are individual and discrete toaccomplish the look and feel of real grass.

BRIEF SUMMARY OF THE INVENTION

Briefly described, and according to one embodiment, the presentinvention relates to a system for manufacturing synthetic yarns used forsynthetic turf. The system includes a plurality of rollers for advancinga plastic sheet along a predetermined path through the system.Initially, as the plastic sheet enters the system, a cooling rollercools one side of the sheet, and then a heating roller heats theopposing side of the sheet to pre-form the plastic sheet such thatsubsequent synthetic yarns made from the sheet will have a curled shape.After the plastic sheet is passed around the alternating cooling andheating rollers, a slitting component engages and slits the plasticsheet longitudinally along the length of the sheet to form a pluralityof single strand synthetic yarns as the sheet advances along thepredetermined path. A drawing component then pulls the single strandsynthetic yarns under tension and heat to stretch and thin the yarns,and also to round or radius the edges of the yarns.

According to one aspect, the cooling roller maintains a temperature ofabout 25° C. and cools the plastic sheet as the plastic sheet enters thesystem. Additionally, the heating roller maintains an temperature ofabout 35° C. and heats the plastic sheet after the plastic sheet ispassed around the cooling roller. According to one aspect, thetemperatures of both the cooling roller and heating roller arecontrolled by the circulation of cold or hot water throughout the insideof the rollers.

According to another aspect, once the single strand synthetic yarns havebeen drawn by the drawing component, the yarns are cut to predeterminedlengths and then reheated to effect a curled shape in the yarns. Thiscurled shape was originally pre-formed in the plastic sheet when it waspassed around the alternating cooling and heating rollers, and thesubsequent reheating stage causes this latent curl to become effected.According to one aspect, the single strand synthetic yarns are appliedto a backing after they have been cut to predetermined lengths butbefore they enter the reheating stage.

According to yet another aspect, the slitting component comprises aplurality of slitting blades that engage and continuously cut theplastic sheet into the plurality of single strand synthetic yarns as thesheet advances along the predetermined path. In one aspect, theplurality of slitting blades are spaced apart at a predetermined equaldistance. This equal distance corresponds to the initial width of thesingle strand yarns, so it can be set by the user of the system to anyinitial width the user desires. Preferably, however, this predetermineddistance is between about 1.00 mm to about 6.00 mm. Alternatively, theplurality of slitting blades may be spaced apart at a plurality ofdifference distances to create single strand synthetic yarns of acorresponding plurality of widths. According to one aspect, the plasticsheet advances through the slitting component at a speed of about 16.6m/min.

According to still another aspect, a pulling and tensioning roller ispositioned to contact the plurality of single strand synthetic yarns ata distance D less than or equal to 1.0 inch after the slitting blades tomaintain tension on the yarns. When the initial yarn width is less than5.00 mm, it is important to retain a distance D of less than or equal to1.0 inch to keep the freshly-cut yarns moving freely through theapparatus, such that they do not become tangled or lose tension.Preferably, the distance D is about ¾ of at inch.

According to a further aspect, a second pulling and tensioning roller ispositioned opposite the first pulling and tensioning roller such thatthe single strand synthetic yarns are pinched between the two rollers tomaintain tension on the yarns. In one aspect, the second pulling andtensioning roller, rather than being directly opposite the first pullingand tensioning roller, is positioned at a distance from the firstpulling and tensioning roller along the predetermined path.

According to another aspect, the drawing component includes a drawingoven for heating the single strand synthetic yarns and a plurality ofdrawing rollers adapted to pull and stretch the yarns. In one aspect,the drawing oven heats the single strand synthetic yarns to atemperature of about 90° C. to about 110° C. The yarns are heated inthis way so that they may be stretched and shaped by the plurality ofdrawing rollers. The heated stretching of the yarns creates a smoothfinish on yarns, and additionally rounds or radiuses the edges andcorners of the yarns. This heated stretching provides a natural seal orfinish on the single strand synthetic yarns giving the yarns a higherresilience and more natural look and feel as compared to other syntheticyarns used for synthetic turf.

According to one aspect, the plurality of drawing rollers create thetension that pulls and stretches the single strand yarns when they arein the drawing oven. After exiting the oven, the yarns are additionallypulled around the plurality of drawing rollers for further shaping andfinishing. In one aspect, the drawing component pulls the plurality ofsingle strand synthetic yarns under tension with a draw ratio of about6:1.

According to an additional aspect of the present embodiment, at leastone of the drawing rollers comprises a heated drawing roller, and atleast one of the rollers comprises a cooled drawing roller. The heateddrawing rollers maintain the temperature of the yarns as they arefurther processed by the rollers, and the cooled drawing rollers coolthe yarns to room temperature as the yarns complete the drawing process.Preferably, the heated drawing rollers maintain a temperature of about90° C. to about 110° C., and the cooled drawing rollers maintain atemperature of about 25° C. According to one aspect, the heated andcooled drawing rollers are heated and cooled in the same manner as theheating and cooling rollers used in an earlier stage of the system.

According to one aspect, the plastic sheet is made of linear low densitypolyethylene (LLDPE), polypropylene, nylon, or any combination of thesematerials. In another aspect, the plastic sheet initially has a widthbetween about 0.5 m to about 3.0 m and a thickness between about 50microns to about 500 microns (1.0×10⁻⁶ meters) before the sheet is slitby the slitting component.

According to still another aspect, after the yarns are drawn andstretched by the drawing component, the final width of the single strandsynthetic yarns will be less than the initial width of the yarnsimmediately after the yarns are slit by the slitting blades. In oneaspect, the final width of the yarns is between about 0.5 mm to about3.0 mm and the thickness of the yarns is between about 25 microns toabout 150 microns.

According to one aspect, at least one of the rollers, pulling andtensioning rollers, and the drawing rollers of the system are driven bya rotational mechanical force to advance the plastic sheet and theresulting single strand synthetic yarns forward through the system alongthe predetermined path. Additionally, at least one of the rollers orpulling and tensioning rollers may be locked in a fixed position so thatit does not rotate with the movement of the plastic sheet and singlestrand synthetic yarns to create added tension on the sheet and yarns.Alternatively, at least one of the rollers or pulling and tensioningrollers may be mounted on bearings such that it may rotate freely withthe movement of the sheet or yarns to allow for smoother movement of thesheet and yarns through the system. Further, at least one of the rollersor pulling and tensioning rollers includes a rough or coarse surface forcreating additional traction to move the sheet or yarns along the path.Preferably, the roller or pulling and tensioning roller(s) that includethe rough surface should be the same roller(s) that are driven by therotational mechanical force.

According to a yet further aspect, the system includes a winder to windthe plurality of single strand synthetic yarns together to form multiplestrand synthetic yarn combinations after the yarns have been drawn bythe drawing component, and a twister to wrap the multiple strandsynthetic yarns combinations around a flanged spool for furtherprocessing.

According to another embodiment, the present invention relates to amethod for manufacturing synthetic yarns used for synthetic turf. Themethod includes advancing a plastic sheet along a predetermined path.The method also includes the steps of cooling one side of the plasticsheet and then immediately heating the other side of the plastic sheetbefore the sheet is cut into single strand synthetic yarns. Thisalternating cooling and heating of opposing sides of the plastic sheetwill eventually result in curled synthetic yarns after the sheet is cutinto yarns and further processed. The method further comprises the stepof continuously slitting the plastic sheet longitudinally into aplurality of single strand synthetic yarns, such that the sheet is slitas a set point along the predetermined path as the sheet advances alongthe path. The yarns are then drawn under tension and heat to stretch andthin the yarns and to round and curve the edges of the yarns.

According to one aspect, one side of the plastic sheet is cooled to atemperature of about 25° C., and the other side of the plastic sheet isheated to a temperature of about 35° C. before the sheet is slit intosingle strand synthetic yarns.

According to another aspect, after the yarns have been drawn undertension and heat, the yarns are cut to predetermined lengths andattached to a backing for further use as synthetic turf. In one aspect,the yarns are reheated after they are cut but before they are attachedto the backing to cause the ends of the yarns to curl. In anotheraspect, the yarns are reheated after they have been cut and attached tothe backing, again to cause the ends of the yarns to curl.

In an additional aspect, the plastic sheet advances along thepredetermined path at a speed of about 16.6 m/min. In one aspect, beforethe plastic sheet is slit, the sheet has a width between about 0.5 m toabout 3.0 m and a thickness between about 50 microns to about 500microns.

According to yet another aspect, the single strand synthetic yarns havewidths between about 1.0 mm to about 6.0 mm before the single strandsynthetic yarns are drawn. In one aspect, the single strand syntheticyarns have widths between about 0.5 mm to about 3.0 mm and thicknessesbetween about 25 microns to about 150 microns after the single strandsynthetic yarns are drawn.

According to still another aspect, the method further comprises the stepof contacting and pulling the single strand synthetic yarns along thepredetermined path immediately after the yarns have been slit tomaintain tension in the yarns. Generally, this contacting and pullingoccurs at a point less than or equal to 1.0 inch after the point inwhich the single strand synthetic yarns were slit.

According to a further aspect, the plurality of single strand syntheticyarns are drawn at a draw ratio of about 6:1. In one aspect, the yarnsare heated to a temperature of about 90° C. to about 110° C. while beingdrawn. The yarns are heated in this way so that they may be stretchedand shaped during the drawing process. The heated stretching of theyarns creates a smooth finish on the yarns, and additionally rounds orradiuses the edges and corners of the yarns. This heated stretchingprovides a natural seal or finish on the single strand synthetic yarnsgiving the yarns a higher resilience and more natural look and feel ascompared to other synthetic yarns used for synthetic turf. Additionally,in some aspects, the single strand synthetic yarns are cooled afterbeing drawn. In one aspect, the yarns are cooled to a temperature ofabout 25° C.

In yet a further aspect, the single strand synthetic yarns are wound andtwisted together after being drawn for further processing.

According to one aspect, the plastic sheet is made of linear low densitypolyethylene (LLDPE), polypropylene, nylon, or any combination of thesematerials.

According to an additional aspect, the present invention also relates tothe single strand synthetic yarns manufactured by a method of thepresent invention. These single strand synthetic yarns are subsequentlyused to make synthetic turf.

These and other embodiments and aspects of the present invention willbecome apparent from the following description of the preferredembodiment taken in conjunction with the following drawings, althoughvariations and modifications therein may be affected without departingfrom the spirit and scope of the novel concepts of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate one or more embodiments of theinvention and, together with the written description, serve to explainthe principles of the invention. Wherever possible, the same referencenumbers are used throughout the drawings to refer to the same or likeelements of an embodiment, and wherein:

FIG. 1A is a flow chart demonstrating the high-level components of thesystem according to embodiments of the present invention.

FIG. 1B is a side view illustrating a slitting station used to slit aplastic sheet into a plurality of single strand synthetic yarns forsynthetic turf according to embodiments of the present invention.

FIG. 2A is a magnified front view illustrating a slitter blade barhaving a plurality of slitting blades used to slit a plastic sheet intoa plurality of single strand synthetic yarns for synthetic turfaccording to embodiments of the present invention.

FIG. 2B is a top view of the plastic sheet and resulting single strandsynthetic yarns as the plastic sheet is slit according to an embodimentof the present invention.

FIGS. 3A-3C illustrate various embodiments of the slitter blade bar,slitting blades and the surrounding rollers.

FIG. 4 is a side view illustrating a series of drawing rollers used tostretch and pull the single strand synthetic yarns to a desired shapeaccording to embodiments of the present invention.

FIG. 5A shows a cross-sectional view of a single strand synthetic yarnafter it has been slit but before it has been drawn.

FIG. 5B shows a cross-sectional view of a single strand synthetic yarnfor synthetic turf after it has been drawn according to embodiments ofthe present invention.

FIG. 6A shows a single strand synthetic yarn with a resulting curled tipaccording to embodiments of the present invention.

FIG. 6B shows a strand of conventional synthetic yarn.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is more particularly described in the followingexamples that are intended as illustrative only since numerousmodifications and variations therein will be apparent to those skilledin the art. Various embodiments of the invention are now described indetail. Referring to the drawings, like numbers indicate like componentsthroughout the views. As used in the description herein and throughoutthe claims that follow, the meaning of “a”, “an”, and “the” includesplural reference unless the context clearly dictates otherwise. Also, asused in the description herein and throughout the claims that follow,the meaning of “in” includes “in” and “on” unless the context clearlydictates otherwise.

The terms used in this specification generally have their ordinarymeanings in the art, within the context of the invention, and in thespecific context where each term is used.

Certain terns that are used to describe the invention are discussedbelow, or elsewhere in the specification, to provide additional guidanceto the practitioner in describing the apparatuses, systems, and methodsof the invention and how to make and use them. For convenience, certainterms may be highlighted, for example using italics and/or quotationmarks. The use of highlighting has no influence on the scope and meaningof a term; the scope and meaning of a term is the same, in the samecontext, whether or not it is highlighted. It will be appreciated thatthe same thing can be said in more than one way. Consequently,alternative language and synonyms may be used for any one or more of theterms discussed herein, nor is any special significance to be placedupon whether or not a term is elaborated or discussed herein. Synonymsfor certain terms are provided. A recital of one or more synonyms doesnot exclude the use of other synonyms. The use of examples anywhere inthis specification, including examples of any terms discussed herein, isillustrative only, and in no way limits the scope and meaning of theinvention or of any exemplified term. Likewise, the invention is notlimited to various embodiments given in this specification. Furthermore,subtitles may be used to help a reader of the specification to readthrough the specification, which the usage of subtitles, however, has noinfluence on then scope of the invention.

Techniques and processes for manufacturing synthetic turf are well knownto those skilled in the art. Therefore, the scope of the disclosure ofthe present invention is limited to the manufacture of synthetic yarnsused for synthetic turf. Generally, the material used for synthetic yarnis linear low density polyethylene (hereinafter “LLDPE”). LLDPE is asubstantially linear polymer, with a significant number of shortbranches, commonly made by copolymerization of ethylene withlonger-chain olefins. LLDPE has higher tensile strength and higherimpact and puncture resistance as compared to other similar materials.It is very flexible and elongates under stress. It can be used to makethin films, with enhanced environmental stress cracking resistance thanother similar materials. Additionally, LLDPE has good resistance tochemicals and ultraviolet radiation. Accordingly, LLDPE is aparticularly well-suited starting material to create synthetic yarn forsynthetic turf.

Referring now to FIG. 1A, the high-level components and steps 10involved in manufacturing synthetic yarns used for synthetic turf areshown according to embodiments of the present invention. Themanufacturing process of synthetic yarn begins with the LLDPE rawmaterial, which is typically in pellet form. The pellets are heated andextruded in a conventional manner at extruder 50 to produce LLDPE filmof a desired thickness and width. The width of the initial LLDPE sheetis typically in a range of about 0.5 meters to about 3.00 meters, andthe thickness of the LLDPE sheet is typically in a range of about 50 toabout 500 microns. Preferably, the LLDPE sheet has a starting width ofabout 1.4 meters and a thickness of about 300 microns for easy handlingand higher efficiency. However, as will be apparent to one havingordinary skill in the art, other widths and thicknesses are possible.

After the LLDPE sheet exits the extruder 50, it enters a slittingstation 100, in which the LLDPE sheet is rolled across opposingtemperature rollers that heat and cool opposing sides of the LLDPE sheetto produce a curl in the finished product synthetic yarn. After theLLDPE sheet is passed around the alternating temperature rollers, thesheet is then slit into single strand synthetic yarns. As will bedescribed in greater detail below, the synthetic yarns areadvantageously slit before they are drawn. Once cut by the slittingstation 100, the plurality of yarn strands enter a drawing oven 60wherein the yarns are heated and drawn (i.e. “stretched”) to a desiredwidth and thickness by being pulled by a plurality of drawing rollers400 on the exit side of the drawing oven 60. Once complete, the finishedyarn product is sent to a winder 70 and a twister 80 to wind the yarnstogether for further processing and installation onto the backing usedfor synthetic turf.

FIG. 1B illustrates a side view of the slitting station 100 and how anLLDPE sheet is slit into a plurality of single strand synthetic yarnsfor use in manufacturing synthetic turf according to embodiments of thepresent invention. The slitting station 100 includes an air knife 120, acooling roller 101, a heating roller 102, a plurality of pulling andtensioning rollers 103, 104, 106, 108, 113, 114, 116, and 118, and aslitter blade bar 110 having a plurality of slitting blades 112. TheLLDPE sheet 200 and resultant slitted single strand synthetic yarns 202are threaded along a predetermined path indicated by arrows 300.

Initially, an LLDPE sheet 200 is extruded from the extruder 50, and isblown onto the cooling roller 101 by the air knife 120. The air knife120 forces the LLDPE sheet 200 against the cooling roller 101 andadditionally stabilizes the sheet. Once on the cooling roller 101, theLLDPE sheet 200 is pulled, in tension, by the pulling and tensioningrollers 103, 104, 106, 108, 113, 114, 116, and 118 around the coolingroller 101 to cool one side of the LLDPE sheet 200 to room temperature,preferably about 25° C. According to one embodiment, the cooling roller101 is cooled internally by cooled water that is circulated throughoutthe inside of the roller in a conventional manner. In this way, thecooling roller 101 cools the LLDPE sheet 200 via conduction.

Once the LLDPE sheet 200 has passed around the cooling roller 101, thesheet is then pulled around a heating roller 102. As shown in FIG. 1B,the heating roller 102 heats the opposing side of the LLDPE sheet 200that was cooled by the cooling roller 101. The LLDPE sheet 200 is passedaround these alternating temperature rollers 101 and 102 to produce afinal product synthetic yarn that has a curled tip, as shown and as willbe described in FIG. 6A. The alternating cooling roller 101 and heatingroller 102 serve to introduce a latent curl to the LLDPE sheet bycooling one side of the sheet while immediately thereafter heating theother side of the sheet, as shown in FIG. 1B. This resulting curl is notrealized, however, until the LLDPE sheet has been fully processed intosynthetic yarns, cut into smaller length segments, and then subsequentlyreheated after being placed onto the backing used for synthetic turf, aswill be described in greater detail below. Additionally, according toone embodiment, the heating roller 102 is heated in the same way thatthe cooling roller 101 is cooled—by heated water that is circulatedthroughout the roller.

As mentioned previously, “flyout” is a major problem with conventionalsynthetic turf. The movement or loss of the sand and rubber infillaround the base of the fibers and yarns when used for synthetic turfcreates an uneven, unsightly, and even dangerous playing surface. Thecurled tips on the synthetic yarns manufactured according to embodimentsof the present invention are desirable because they help to keep theinfill in place around the base of the “grass” blades once the syntheticturf is in use. These curled tips keep the infill from being blown awayor significantly moved because they bend downward, thus providing acover for the infill. With straight, conventional fibers, however, thereis no covering keeping the infill in place, and thus “flyout” frequentlyoccurs. Additionally, the curled tips of the yarns produced according toembodiments of the present invention give the synthetic yarns a morenatural look and feel as compared to non-curled, conventional yarns.

Still referring to FIG. 1B, after the LLDPE sheet 200 is passed aroundthe heating roller 102, the sheet is fed along the LLDPE sheet path asindicated by arrows 300. At least one of the pulling and tensioningrollers 103, 104, 106, 108, 113, 114, 116, and 118 is powered by arotating mechanical force to move the LLDPE sheet 200 forward along thepath. One or more of these pulling and tensioning rollers are used tocreate tension such that the LLDPE sheet 200 is moved forward in aconsistent and flat motion. While a wide range of speeds are possible tomove the LLDPE sheet through the slitting station 100, a speed of about16.6 m/min is preferable. In some embodiments, one or more of theplurality of pulling and tensioning rollers 103, 104, 106, 108, 113,114, 116, and 118 are stationary and will not roll with the movement ofthe LLDPE sheet 200 in order to create added tension upon the sheet. Inother embodiments, one or more of the plurality of pulling andtensioning rollers are mounted on two bearings, one on each end, suchthat these rollers rotate along with the movement of the LLDPE sheet200.

As the LLDPE sheet 200 is pulled along the path indicated by arrows 300,it is cut longitudinally along its length by the slitter blade bar 110and corresponding slitting blades 112. According to one embodiment ofthe present invention, the slitter blade bar 110 has two primarypositions. In its initial or disengaged position, the slitter blade bar110 is raised such that the slitting blades 112 are not in contact withthe LLDPE sheet 200 (not shown). This initial position allows the LLDPEsheet 200 to be fed through all of the pulling and tensioning rollers103, 104, 106, 108, 113, 114, 116, and 118 to create the requiredtension on the LLDPE sheet before the cutting begins. The second orengaged position is the primary position of the slitting station 100,wherein the slitter blade bar 110 is lowered once the system beginsrunning such that the blades 112 become engaged with and continuouslyslit the LLDPE sheet 200 into a plurality of single strand syntheticyarns 202 as the sheet 200 is advanced. FIG. 1B shows the slitter bladebar 110 and slitting blades 112 in this second, engaged position.Preferably, pulling and tensioning roller 108 rotates with the movementof the LLDPE sheet 200 to allow for smooth transition of the LLDPE sheetinto the slitting blades 112.

Referring still to FIG. 1B, once the LLDPE sheet 200 has been cut intosingle strand synthetic yarns 202 by the slitting blades, the yarns 202are pulled by the pulling and tensioning rollers 113, 114, 116, and 118for further processing. If a preferred embodiment, pulling andtensioning roller 113 is driven by a rotational mechanical force to keepthe strands taught and moving smoothly after they are cut. Additionally,in one embodiment of the present invention, pulling and tensioningroller 113 has a rough or coarse outer surface to create enough tractionto keep the single strand synthetic yarns 202 moving forward smoothly.

FIG. 2A is a magnified front view showing the slitter blade bar 110 witha plurality of slitting blades 112 for slitting the LLDPE sheet into aplurality of single strand synthetic yarns for synthetic turf accordingto one embodiment of the present invention. The slitting blades 112comprise razor blades or any other blades particularly adapted formaking fine, precise cuts. The slitting blades 112 are typically spacedapart at a predetermined equal distance L that cuts the LLDPE sheet 200into single strand synthetic yarns 202 with the same correspondingstrand width L, as shown in FIG. 5A. This predetermined distance L is inthe range of about 1.00 mm to about 6.00 mm, and preferably is either3.00 mm or 4.00 mm. Once, the yarns are cut, they will be stretched andthinned by the drawing process, so the initial width of cut L must belarger than the final desired width of the yarns L′. While the resultingstrand width L′ for a particular cut width L may vary depending on thesubsequent draw ratio created by the drawing rollers, a cut width of3.00 mm will typically produce a final product single strand syntheticyarn 202 with a width of 1:3 mm, and a cut width of 4.00 mm willtypically produce a final product single strand synthetic yarn with awidth of 1.6 mm. In an alternative embodiment (not shown), the slittingblades 112 can be set apart at a variety of different distances L toenable a sheet of LLDPE to produce two or more sized strands of yarnfrom the single sheet of LLDPE.

FIG. 2B shows a top view of the LLDPE sheet 200 as it passes under theslitter blade bar 110 and through the slitting blades 112, and is cutinto single strand synthetic yarns 202 of equal size L. As shown in FIG.2B, the single strand synthetic yarns 202 are continually cut by theslitting blades 112 to produce discrete, continuous strands.

Referring now to FIGS. 3A, 3B, and 3C, various positions of the pullingand tensioning rollers 108, 113, and 115 around the slitter blade bar110 and slitting blades 112 are shown according to different embodimentsof the present invention. In FIG. 3A, pulling and tensioning roller 113is positioned such that the point of contact between the roller and thesingle strand synthetic yarns 202 measures a distance D from the pointof contact where the slitter blades 112 engage the LLDPE sheet 200. Thispulling and tensioning roller 113 is positioned under the single strandsynthetic yarns 202 after they are cut from the LLDPE sheet 200 by theslitting blades 112. Additionally, pulling and tensioning roller 113 ispositioned such that its central axis is parallel with the central axisof the slitter blade bar 110.

When the distance L between the slitter blades 112 is less than 5.00 mm,it can be difficult to keep the slitted single strand synthetic yarns202 moving straight and smoothly with the pulling and tensioning roller113. Accordingly, the predetermined distance D is typically less than orequal to 1 inch, and preferably about ¾ of an inch.

In one embodiment, as shown in FIG. 3B, an additional pulling andtensioning roller 115 is added to provide more stability and directionto the single strand synthetic yarns 202 as they pass through theslitting blades 112. The additional pulling, and tensioning roller 115is added on the opposite side of the single strand synthetic yarns 202from roller 113, such that the material is pulled and pinched betweenthese two rollers 113 and 115. Preferably, pulling and tensioning roller115 is driven by a rotational mechanical force, similar to roller 113.Also, the distance D remains less than or equal to 1 inch, andpreferably about ¾ of an inch.

In another embodiment, as shown in FIG. 3C, the additional pulling andtensioning roller 115 is again added on the opposite side of the singlestrand synthetic yarns 202 from pulling and tensioning roller 113, butin this embodiment roller 115 is placed at some distance after roller113 along the processing path of the single strand synthetic yarns. Thisroller configuration produces slightly different amounts of tension onthe LLDPE sheet 200 and resulting single strand synthetic yarns 202 ascompared to the configurations shown in FIGS. 3A and 3B. Thus, thepulling and tensioning rollers 108, 113, and 115 can be moved andpositioned by the user to produce a certain desired level of tension onthe LLDPE material as it progresses through the system, and, inparticular, through the slitting blades 112.

As will be understood by one having ordinary skill in the art, othervariations of rollers, including the addition of further pulling andtensioning rollers, are also possible to effectively create tension andcorresponding smooth movement of the single strand synthetic yarns 202and LLDPE sheet 200. Regardless, it is, important to note that thedistance between where the slitting blades 112 engage the LLDPE sheet200 and the point of contact between the resulting yarns 202 and thepulling roller 113 is kept at a distance D that is typically less than 1inch, and preferably about ¾ of an inch.

Referring, again to FIGS. 1A and 1B, after the single strand syntheticyarns 202 are slit by the slitting blades 112, the yarns are fed intothe drawing oven 60 by pulling and tensioning rollers 116 and 118.Preferably, at least one of rollers 116 and 118 is driven by arotational mechanical force. In one embodiment of the present invention,the rollers 116 and 118 slow down the single strand synthetic yarns 202as the yarns enter the drawing oven 60 to create added tension in theyarns as they are heated by the oven and subsequently stretched by theseries of drawing rollers 400. According to one embodiment of thepresent invention, the temperature inside the drawing oven 60 ispreferably between about 90° C. and about 110° C., but as will beapparent to those having ordinary skill in the art, other oventemperatures are possible.

As shown in FIG. 4, a series of drawing rollers 400 for stretching theslit single strand synthetic yarns 202 to a desired shape areillustrated according to embodiments of the present invention. Theseries of drawing rollers 400 include a plurality of pulling andtensioning rollers and a plurality of drawing rollers. In the embodimentshown in FIG. 4, the pulling and tensioning rollers include rollers 402,404, 406, and 408, and the drawing rollers include rollers 410, 412,414, 416, 418, 420, 422, 424, 426, and 428. The single strand syntheticyarns 202 are threaded around the rollers along a path indicated byarrows 300. As will be understood by one of ordinary skill in the art,other positions and numbers of rollers are possible other than theconfiguration shown in FIG. 4.

As the single strand synthetic yarns 202 progress through the drawingoven 60, the yarns are pulled and stretched out of the oven by pullingand tensioning rollers 402 and 404, and additionally by the drawingrollers 410, 412, 414, 416, 418, 420, 422, 424, 426, and 428. It is thispulling and stretching of the yarns 202 while they are in the oven 60that gives the yarns of the present invention their added resilience andfinishing, as will be described in greater detail below. Essentially,the single strand synthetic yarns 202 are restrained somewhat by theslower-spinning rollers 116 and 118 at the front end of the oven 60while the yarns 202 are pulled on the other side of the oven 60 by theseries of drawing rollers 400. This differential in speed and tension iswhat causes the yarns to stretch while traveling through the drawingoven 60. Accordingly, at least one of the pulling and tensioning rollers402 and 404 and the drawing rollers 410, 412, 414, 416, 418, 420, 422,424, 426, and 428 is driven by a rotational mechanical force.

The number of rollers used in the series of drawing rollers 400, as wellas the speed at which the rollers are rotating, dictates the drawingratio exerted upon the single strand synthetic yarns 202. While a widerange of drawing ratios may be used within embodiments of the presentinvention, a ratio of about 6:1 is preferable. If the drawing ratio istoo low, the single strand synthetic yarns 202 may become too soft andstick to the rollers. If the drawing ratio is too high, the resultingyarns will likely be stiff and undesirable. Accordingly, althoughseveral different drawing ratios are possible under embodiments of thepresent invention, a ratio of about 6:1 produces high quality fiberswith the system described herein.

According to further embodiments of the present invention, the pluralityof drawing rollers 410, 412, 414, 416, 418, 420, 422, 424, 426, and 428includes a plurality of cooled drawing rollers and a plurality of heateddrawing rollers. In the embodiment shown in FIG. 4, the heated drawingrollers include rollers 410, 412, 414, 416, 418, 420, and 422, and thecooled drawing rollers include rollers 424, 426, and 428. These drawingrollers are heated and cooled conventionally by hot or cold water thatis circulated throughout the inside of the rollers, just like thecooling roller 101 and heating roller 102. The heated drawing rollers410, 412, 414, 416, 418, 420, and 422 remain at a temperature of about90° C. to about 110° C. to maintain the heat and elasticity of thesingle strand synthetic yarns 202 as they are pulled and stretchedaround the heated drawing rollers after exiting the drawing oven 60. Thecooled drawing rollers 424, 426, and 428 are kept at a temperature ofabout 25° C. to cool the yarns 202 to room temperature as they completethe drawing process. As will be understood by one having ordinary skillin the art, however, the number, variation, and temperature of theheated and cooled drawing rollers may vary at the operator's discretionto produce yarns or fibers of different properties and qualities.

After the single strand synthetic yarns 202 have been sufficientlydrawn, the yarns are moved along the path 300 by pulling and tensioningrollers 406 and 408 for further processing. Thus, at least one ofpulling and tensioning rollers 406 and 408 should be driven by arotational mechanical force.

FIG. 5A shows a cross-sectional view of a single strand synthetic yarn202 after it has been cut by the slitting blades 112, but before it hasbeen drawn. FIG. 5B demonstrates a cross-sectional view of the same yarnafter it has passed through the drawing oven 60 and drawing rollerdevice 400. As shown in FIG. 5A, the pre-drawn yarn has a width L and athickness T. As shown in FIG. 5B, the post-drawn yarn has a decreasedwidth L′ and decreased thickness T′ due to the stretching and pullingcaused by the drawing process. Additionally, the corners and edges ofthe post-drawn yarn have been naturally rounded from the drawingprocess, as will be described in greater detail below. The cross-sectionof the yarn shown in FIG. 5B represents a preferred cross-section of ayarn produced according to embodiments of the present invention.

In one embodiment, before the single strand synthetic yarn 202 isdrawnn, the yarn has a width L in the range of about 1.00 mm to about6.00 mm, and a thickness T in the range of about 50 microns to about 500microns. After the yarn 202 ,is drawn,'the′ resulting width L′ andthickness T′ may vary depending on the draw ratio and heating oven 60temperature, but the preferable width L′ is in the range of about 1.3 mmto about 1.6 mm, and the preferable thickness T′ is in the range ofabout 100 microns to about 135 microns. As mentioned previously, astarting width L of 3.00 mm will generally produce yarns, with a finalwidth L′ of 1.3 mm, and a starting width L of 4.00 mm will generallyproduce yarns with a final width L′ of 1.6 mm according to embodimentsof the present invention.

One benefit of drawing the yarns 202 after they have been slit accordingto embodiments of the present invention is that the heated stretching ofthe yarns naturally rounds off or radiuses the corners and edges of theyarns, as shown in FIG. 5B. As the yarns 202 are pulled through thedrawing oven 60, the edges of the yarns are pulled and heated, causingthem to melt and become round. These rounded edges produce a morenatural look and feel to the yarns, and they eliminate the rough orsharp edges present on the yarns immediately after cutting, as shown inFIG. 5A. As mentioned previously, yarns with rough edges can causeinjury or irritation to people who fall or slide on synthetic turf thatincorporates rough-edged yarns. The yarns produced from embodiments ofthe present invention have smooth, rounded edges, which are highlydesirable.

Additionally, drawing the single strand synthetic yarns 202 through thedrawing oven 60 produces a natural seal or finishing on the yarns,thereby increasing the overall resilience of the yarns. This seal isagain caused by the heated stretching of the yarns 202 as they aredrawn. As mentioned previously, cut yarns that are not finished orsealed begin to deteriorate quickly once in use on synthetic turfbecause they lack the resiliency and strength of sealed or finishedyarns. The drawing process employed by embodiments of the presentinvention creates a natural seal on the finished yarns that is simplynot present in many other yarns.

According to embodiments of the present invention, after the singlestrand synthetic yarns 202 exit the series of drawing rollers 400, theyarns are passed on to conventional winder and twister stations 70, 80respectively for further processing. Thereafter, when the yarns 202 areready for use in production, the yarns are cut into smaller sections andattached to a synthetic rubber backing (either woven or nonwoven) by atufting process (not shown). The yarn and synthetic backing combinationare moved onto a tentering system (a chain link system with needlesaround its edges) that grabs the combination and moves it under acoating bar, wherein the backing is coated with polyurethane or anothersimilar adhesive. At this stage, the yarn is held upside down by thetentering system, such that the single strand synthetic yarns 202 arehanging downward, with the coated backing facing upward. The backing andyarns are then heated to cure the adhesive to permanently attach theyarns to the backing, and to effect the curled tip in the yarns. In oneembodiment, this heating comprises sending the yarn and backingcombination through three curing ovens, with each oven heating thecombination to a temperature of about 160° C. to about 220° C. Thecombination spends approximately 1-3 minutes in each respective curingoven. The heat produced by the curing ovens is a steam coil heat focusedpredominantly on the backing. The single strand synthetic yarns 202receive indirect heat while the yarns are facing downward.

When the yarns 202 that are manufactured according to embodiments of thepresent invention are heated during this final curing process, theydevelop a curled tip, as shown in FIG. 6A. The curl in the yarns is aresult of the LLDPE sheet 200 being initially passed around thealternating cooling roller 101 and heating roller 102 to cool and heatopposing sides of the sheet 20 before the sheet 200 is slit into yarns202. This curl remains latent in the yarns 202 until they are drawn, cutinto smaller sections, and finally heated in the curing ovens with thebacking. Accordingly, the alternating temperature, rollers 101, 102serve to pre-form the plastic sheet with a curl, but that curl is noteffected until final cutting and heating. Alternatively, FIG. 6Bdemonstrates a conventional yarn 604 that has not undergone any sort ofcurling treatment. The preferable curled yarn 602 not only helps toretain infill on synthetic turf, as described previously, but also looksand feels more like real grass.

According to one embodiment, the single strand synthetic yarns 202 arecut and reheated after the drawing process to produce the curled tip inthe yarns, without being placed onto the rubber backing. Accordingly,attachment to the rubber backing is not necessary to effect the curledtip in the yarns. In this embodiment, the yarns 202 are laid out on atray and heated in the curing ovens as described above.

According to one embodiment of the present invention, before the singlestrand synthetic yarns 202 are attached to a backing for use assynthetic turf, the yarns are wound together to form multiple strandsynthetic yarn combinations via a winder 70 (not shown). Also, becauseyarns produced by embodiments of the present invention are individual,discrete, and smooth, they often are twisted around a roller with twobookends similar to a spool via a twister 80 to keep the yarns fromsliding off the spool, and the spool is used to transport the yarns forfurther processing (not shown).

The foregoing description of the exemplary embodiments of the inventionhas been presented only for the purposes of illustration and descriptionand is not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Many modifications and variations are possiblein light of the above teaching.

The embodiments were chosen and described in order to explain theprinciples of the invention and their practical application so as toenable others skilled in the art to utilize the invention and variousembodiments and with various modifications as are suited to theparticular use contemplated. Alternative embodiments will becomeapparent to those skilled in the art to which the present inventionpertains without departing from its spirit and scope. Accordingly, thescope of the present invention is defined by the appended claims ratherthan the foregoing description and the exemplary embodiments describedtherein.

1. A system for manufacturing single strand synthetic yarns forsynthetic turf, comprising: a plurality of rollers for advancing a sheetof plastic along a predetermined path within the apparatus; a slittingcomponent for receiving the plastic sheet and slitting the plastic sheetlongitudinally along the length of the sheet to form a plurality ofsingle strand synthetic yarns as the plastic sheet advances along thepredetermined path; and a drawing component positioned along thepredetermined path after the slitting component for pulling theplurality of single strand synthetic yarns under tension and heat tostretch and thin the yarns and further to round the edges of the yarns.2. The system of claim 1, further comprising a plurality of differentialtemperature rollers for alternatively heating and cooling opposing sidesof the plastic sheet before the plastic sheet is cut by the slittingcomponent.
 3. The system of claim 2, wherein the plurality ofdifferential temperature rollers alternatively cool one side of theplastic sheet to a temperature of about 25° C. and heat the other sideof plastic sheet to a temperature of about 35° C.
 4. The system of claim2, further comprising a reheating component for reheating the pluralityof single strand synthetic yarns after the yarns have passed through thedrawing component and after the yarns have been cut to predeterminedlengths, wherein the reheating causes the ends of the cut yarns to curl.5. The system of claim 1, wherein the slitting component comprises aplurality of slitting blades that engage and continuously cut theplastic sheet into the plurality of single strand synthetic yarns as thesheet advances along the predetermined path.
 6. The system of claim 5,wherein the plurality of slitting blades are spaced apart at apredetermined equal distance between about 1.0 mm to about 6.0 mm. 7.The system of claim 5, wherein the plurality of slitting blades arespaced apart at a plurality of different distances to create singlestrand synthetic yarns of a corresponding plurality of widths.
 8. Thesystem of claim 5, further comprising a first pulling and tensioningroller positioned to contact the plurality of single strand syntheticyarns at a distance less than or equal to 1.0 inch after the slittingblades to maintain tension on the yarns.
 9. The system of claim 8,further comprising a second pulling and tensioning roller positionedopposite the first pulling and tensioning roller such that the pluralityof single strand synthetic yarns are pinched between the first pullingand tensioning roller and the second pulling and tensioning roller tomaintain tension on the yarns.
 10. The system of claim 9, wherein thesecond pulling and tensioning roller is positioned at a predetermineddistance from the first pulling and tensioning roller along thepredetermined path.
 11. The system of claim 1, wherein the plastic sheetadvances through the slitting component at a speed of about 16.6 m/min.12. The system of claim 1, wherein the drawing component includes adrawing oven for heating the plurality of single strand synthetic yarnsand a plurality of drawing rollers adapted to stretch and shape theplurality of single strand synthetic yarns.
 13. The system of claim. 12,wherein the drawing oven heats the single strand synthetic yarns to atemperature between about 90° C. to about 110° C.
 14. The system ofclaim 12, wherein at least one of the plurality of drawing rollers heatsthe plurality of single strand synthetic yarns and wherein at least oneof the plurality of drawing rollers cools the plurality of single strandsynthetic yarns after the yarns exit the drawing oven.
 15. The system ofclaim 14, wherein the plurality of single strand synthetic yarns areheated by a heated drawing roller to a temperature between about 90° C.to about 110° C. and are cooled by a cooled drawing roller to atemperature of about 25° C.
 16. The system of claim 1, wherein thedrawing component pulls the plurality of single strand synthetic yarnsunder tension with a draw ratio of about 6:1.
 17. The system of claim 1,wherein the plastic sheet provided to the slitting component has a widthbetween about 0.5 m to about 3.0 m and a thickness between about 50microns to about 5.00 microns.
 18. The system of claim 1, wherein theplurality of single strand synthetic yarns have a width between about0.5 mm to about 3.0 mm and a thickness between about 25 microns to about150 microns after the yarns have been formed by the slitting componentand heated and stretched by the drawing component.
 19. The system ofclaim 1, further comprising a winder to wind the plurality of singlestrand synthetic yarns together to form multiple strand synthetic yarncombinations after the yarns have been drawn by the drawing componentand a twister to wrap the multiple strand synthetic yarn combinationsaround a flanged spool for further processing.
 20. The system of claim1, wherein the plastic sheet comprises linear low density polyethylene(LLDPE), polypropylene, nylon, or any combination thereof.
 21. A systemfor manufacturing single strand synthetic yarns for synthetic turf,comprising: a plurality of pulling and tensioning rollers for advancinga plastic sheet along a predetermined path within the system; a seriesof alternating temperature rollers for heating and cooling opposingsides of the plastic sheet as the sheet advances along the predeterminedpath; a plurality of slitting blades for slitting the plastic sheet toform a plurality of single strand synthetic yarns after the plasticsheet has passed around the alternating temperature rollers, wherein theslitting blades engage and continuously cut the plastic sheet as thesheet is advanced along the predetermined path; a drawing oven forheating the plurality of single strand synthetic yarns once the yarnshave been cut by the slitting blades, wherein the drawing oven heats theplurality of single strand synthetic yarns to assist in a heatedstretching of the yarns; and a series of drawing rollers adapted fortensionally pulling the plurality of single strand synthetic yarnsthrough the drawing oven to produce the heated stretching of the yarns,wherein the heated stretching elongates and shapes the yarns andadditionally rounds the edges of the yarns.
 22. The system of claim 21,further comprising a reheating component for reheating the plurality ofsingle strand synthetic yarns after the yarns have passed through theseries of drawing rollers and after the yarns have been cut topredetermined lengths, wherein the reheating causes the ends of the cutyarns to curl.
 23. The system of claim 21, wherein at least one pullingand tensioning roller is positioned to contact the plurality of singlestrand synthetic yarns at a distance less than or equal to 1.0 inchafter the slitting blades to maintain tension on the yarns.
 24. Thesystem of claim 21, wherein at least one drawing roller in the series ofdrawing rollers heats the plurality of single strand synthetic yarns andwherein at least one drawing roller in the series of drawing rollerscools the plurality of single strand synthetic yarns after the yarnsexit the drawing oven.
 25. The system of claim 21, wherein the plasticsheet comprises linear low density polyethylene (LLDPE), polypropylene,nylon, or any combination thereof.
 26. A method for manufacturing singlestrand synthetic yarns for synthetic turf, comprising the steps of:advancing a plastic sheet along a predetermined path; slitting theplastic sheet longitudinally into a plurality of single strand syntheticyarns, wherein the plastic sheet is slit at a set point along thepredetermined path as the plastic sheet advances along the predeterminedpath; and, thereafter, drawing the plurality of single strand syntheticyarns under tension and heat to stretch and thin the yarns and furtherto round the edges of the yarns.
 27. The method of claim 26, furthercomprising the step of alternatively heating and cooling opposing sidesof the plastic sheet before the sheet is slit into the plurality ofsingle strand synthetic yarns.
 28. The method of claim 27, wherein theplastic sheet is alternatively cooled to a temperature of about 25° C.and heated to a temperature of about. 35° C.
 29. The method of claim 27,further comprising the step of cutting the plurality of single strandsynthetic yarns to desired lengths after the yarns have been drawn andattaching the cut single strand synthetic yarns to a backing.
 30. Themethod of claim 29, further comprising the step of reheating the cutsingle strand synthetic yarns before the yarns have been attached to thebacking to produce a curled shape in the yarns.
 31. The method of claim29, further comprising the step of reheating the cut single strandsynthetic yarns after the yarns have been attached to the backing toproduce a curled shape in the yarns.
 32. The method of claim 26, whereinthe plastic sheet advances along the predetermined path at a speed ofabout 16.6 m/min.
 33. The method of claim 26, wherein the step ofslitting the plastic sheet includes continuously slitting the sheet atthe set point as the plastic sheet advances along the predeterminedpath.
 34. The method of claim 26, wherein before the plastic sheet isslit the sheet has a width between about 0.5 m to about 3.0 m and athickness between about 50 microns to about 500 microns.
 35. The methodof claim 26, wherein the plurality of single strand synthetic yarns areslit such that each single strand synthetic yarn has a width of betweenabout 1.0 mm to about 6.0 mm before the plurality of single strandsynthetic yarns are drawn.
 36. The method of claim 26, wherein theplurality of single strand synthetic yarns have a width between about0.5 mm to about 3.0 mm and a thickness between about 25 microns to about150 microns after the yarns have been slit and drawn.
 37. The method ofclaim 26, further comprising the step of contacting and pulling theplurality of single strand synthetic yarns along the predetermined pathimmediately after the yarns have been slit to maintain tension on theyarns as the yarns progress along the predetermined path, wherein thecontacting and pulling occurs at a point along the predetermined pathless than or equal to 1.0 inch after the set point at which theplurality of single strand synthetic yarns are slit.
 38. The method ofclaim 26, wherein the plurality of single strand synthetic yarns aredrawn at a draw ratio of about 6:1.
 39. The method of claim 26, whereinthe plurality of single strand synthetic yarns are heated to atemperature between about 90° C. to about 110° C. while being drawn. 40.The method of claim 26, wherein the step of drawing the plurality ofsingle strand synthetic yarns further comprises the step of cooling theplurality of single strand synthetic yarns after the yarns have beenheated and stretched.
 41. The method of claim 40, wherein the pluralityof single strand synthetic yarns are cooled to a temperature of about25° C.
 42. The method of claim 26, further comprising the step ofwinding the plurality of single strand synthetic yarns together to formmultiple strand synthetic yarn combinations after the yarns have beendrawn and twisting the multiple strand synthetic yarn combinationstogether for further processing.
 43. The method of claim 26, wherein theplastic sheet comprises linear low density polyethylene (LLDPE),polypropylene, nylon, or any combination thereof.
 44. A single strandsynthetic yarn manufactured according to the method described in claim26.
 45. A method for manufacturing single strand synthetic yarns forsynthetic turf, comprising the steps of: advancing a plastic sheet alonga predetermined path; alternatively heating and cooling opposing sidesof the plastic sheet; slitting the plastic sheet into a plurality ofsingle strand synthetic yarns after the opposing sides of the plasticsheet have been alternatively heated and cooled, wherein the plasticsheet is continuously slit at a set point along the predetermined pathas the plastic sheet advances along the predetermined path; heating theplurality of single strand synthetic yarns once the yarns have been cutfrom the plastic sheet by the slitting blades, wherein the yarns areheated to assist in a heated stretching of the yarns; and, thereafterpulling the plurality of single strand synthetic yarns under tension andheat to generate the heated stretching of the yarns, wherein the heatedstretching elongates and shapes the yarns and additionally rounds theedges of the yarns.
 46. The method of claim 45, further comprising thestep of cutting the plurality of single strand synthetic yarns todesired lengths after the yarns have been pulled under tension and heatand attaching the cut single strand synthetic yarns to a backing. 47.The method of claim 46, further comprising the step of reheating the cutsingle strand synthetic yarns before the yarns have been attached to thebacking to produce a curled shape in the yarns.
 48. The method of claim46, further comprising the step of reheating the cut single strandsynthetic yarns after the yarns have been attached to the backing toproduce a curled shape in the yarns.
 49. The method of claim 45, furthercomprising the step of contacting and pulling the plurality of singlestrand synthetic yarns along the predetermined path immediately afterthe yarns are slit to maintain tension on the yarns as the yarnsprogress along the predetermined path, wherein the contacting andpulling occurs at a point along the predetermined path less than orequal to 1.0 inch after the set point at which the plurality of singlestrand synthetic yarns are slit.
 50. The method of claim 45, wherein thestep of pulling the plurality of single strand synthetic yarns undertension and heat further comprises the step of cooling the plurality ofsingle strand synthetic yarns after the yarns have been heated andstretched.
 51. The method of claim 45, wherein the plastic sheetcomprises linear low density polyethylene (LLDPE), polypropylene, nylon,or any combination thereof.
 52. A single strand synthetic yarnmanufactured according to the method described in claim 45.